Nec Corporation

Ntt Docomo, Inc.

Masayuki Kimata

Shousei Yoshida

Yoshikazu Kakura

Mamoru Sawahashi

Kenichi Higuchi

Akihisa Ushirokawa

Kengo Oketani

Junichiro Kawamoto

Noriyuki Maeda

Shingo Kikuchi

Kunifusa Maruyama

Ryosuke Uchida

Channel estimator, based on the received signal received through a radio channel, estimates an estimated value of a channel showing channel characteristics of the radio channel. Correlation value calculatorcalculates a time domain channel correlation value showing the time correlation of the radio channel, based on the estimated value of the channel. Channel power calculatorcalculates channel power as the power of the received signal, based on the estimated value of the channel. Noise power calculatorcalculates noise power as the power of the noise component contained in the received signal. Correctorcorrects the channel power based on the noise power and corrects the time domain channel correlation value based on the corrected channel power and the noise power. Fading Doppler frequency estimatorestimates the fading Doppler frequency based on the corrected time domain channel correlation value.

Fading doppler frequency estimation device and fading doppler frequency estimation method

In a reception method and a receiver, a base station corrects a frequency offset contained in a reception signal from each user terminal and realizes excellent reception characteristics by using a simple receiver mechanism for performing frequency domain processing in a radio system using a frequency division multiplex (FDM) method. The base station includes: a DFT section that converts reception signals from a plurality of mobile stations communicating by radio communication using FDM all at once into the frequency domain; a demapping section that recognizes, from the frequency domain signals, user signals corresponding to respective mobile stations by using sub-carriers selected in association with respective mobile stations; a correction signal generation section generating a correction signal correcting a user signal frequency offset for each user signal; a frequency conversion section that corrects the frequency offset of the user signal by the correction signal; and a demodulation section that demodulates each of the corrected user signals.

Reception method and receiver

A receiving device includes a channel estimating section that performs a correlating process for a received reference signal in which a single carrier signal was transformed into a frequency domain signal and a pre-stored reference signal so as to obtain estimated channel values; a compensation coefficient computing section that computes compensation coefficients corresponding to residual multipath interferences based on a bit likelihood; a weight computing section that computes equalized weights based on the estimated channel values and the compensation coefficients; an equalizing filter that generates an equalized signal by equalizing process for the received signal that is the frequency domain signal based on the equalized weights; a residual interference replica generating section that generates residual multipath interference replicas based on frequency domain symbol replicas, the estimated channel values, and the equalized weights; and a subtracting section that subtracts the residual multipath interference replicas from the equalized signal.

Receiving device, receiving method, and program

A coherent bandwidth calculation unit () calculates a coherent bandwidth based on a channel response in the time domain obtained from reception signals (R-R) for each path between transmitting antennas and receiving antennas. A weight calculation control unit () determines target subcarriers of equalization weight calculation based on the coherent bandwidth. A weight calculation unit () calculates the equalization weight of each target subcarrier. A weight interpolation unit () performs interpolation processing using the equalization weights so as to obtain equalization weights for the subcarriers that have not undergone equalization weight calculation yet.

MIMO receiving apparatus and method

The present invention provides a channel estimation apparatus in which channel estimation may be made higher than heretofore in accuracy and may be used for calculating the weight for an equalization filter to achieve an optimum equalizing performance. A subcarrier copying unitcopies K items of end-side subcarriers, using the channel estimation obtained by a correlation processing unitand K which is a subcarrier copy number. An IDFT unittransforms the channel estimation obtained at the subcarrier copying unitinto the time domain channel response. A noise path removing unitremoves noise paths from the channel response output from the IDFT unit. A DFT unitperforms DFT of the channel response, from which the noise paths are removed by the noise path removing unit, to output a noise-suppressed frequency domain channel estimation value. A weight calculation unitinputs the frequency domain channel estimation value output from the DFT unitto calculate an equalizing weight.

Apparatus for channel estimation, apparatus for equalization and method for equalization

Disclosed is a MIMO receiving apparatus in which a residual interference calculation unit () inputs noise-suppressed frequency domain channel estimation values, output from FFT units (--to-M-N), equalizing weights calculated by a weight calculating unit (), equalized signals from equalization processing by an equalization filter () and reference signals generated by reference signal generating units (-to-M) to calculate a residual interference, and the likelihood correction units (-to-M) receive time domain equalized signal from the IDFT units (-to-M) and the residual interference calculated by the residual interference calculation unit () to correct the likelihood of the equalized signal (FIG.).

Receiving apparatus and method

In a MIMO receiving apparatus, the signals of single carriers transmitted from a plurality of transmission antennas are received by a plurality of reception antennas (-through-N) and then separated according to frequency ranges. In this MIMO receiving apparatus, interference replicas of the antennas are eliminated from the received signals (by subtractor) before equalizing the two-dimensional frequency ranges, and non-distortion signal replicas are added (by a demodulating part) to the signals from which the interference replicas of the antennas have been eliminated after equalizing the two-dimensional frequency ranges.

MIMO receiving apparatus and receiving method

A receiving apparatus is provided in which a single carrier signal is received by a plurality of receiving antennas, and multipath equalization and other cell interference suppression are carried out in a frequency domain at a same time. A plurality of antennas-to-N receives the single carrier signal. The DFT sections-to-N converts the reception signals into frequency domain signals. A channel estimating sectionestimates a channel gain of a desired user signal by using pilot reception signals. An interference correlation matrix estimating sectionestimates an interference correlation matrix from the pilot reception signals and a channel estimation value. A weight calculating section. A weight calculating sectionreceives the channel estimates and the interference correlation matrix and calculates equalization weights. An equalizing sectionperforms multipath equalization and other cell interference suppression to the desired user signal in a frequency domain. An IDFT sectionconverts an equalization signal into a signal in a time domain.

Receiving apparatus and mobile communication system

A priority computation process computes a priority of each user for each RB (Resource Brock) using a reception SINR. A maximum priority user selection/RB allocation process selects a user with the maximum priority for an unallocated RB and allocates the RB to the user. A frequency axis/space axis unallocated RB presence determination process proceeds to scheduling for a next user if there is an unallocated RB on the frequency or space axis. A projected channel vector update process updates a projected channel vector of an unselected user by GS orthogonalization. An orthogonal coefficient computation process computes an orthogonal coefficient. A corrected SINR computation process computes a corrected SINR. A next MIMO layer priority computation process computes priorities of unselected users for a corresponding RB in the next multiple MIMO layer. The priorities of the unselected users are used in the next user scheduling processing.

Scheduling method for multi-user MIMO in which resource blocks are allocated based on priorities

Provided are a channel estimation device and an equalization device capable of achieving high channel estimation accuracy with less amount of calculation processing. The equalization device includes: a channel estimation section including a ZF calculation/clipping processing section and correlation processing section; a weight calculation section; and an equalization filter. The ZF calculation/clipping processing section uses a signal obtained by converting a pilot code into a frequency domain to calculate a pilot reference signal according to a Zero Forcing (ZF) method and clips the gain of the calculated pilot reference signal to a predetermined value to generate a clipped pilot reference signal. The correlation processing section performs correlation between a pilot reception signal in the frequency domain and clipped pilot reference signal to estimate channel characteristics of the frequency domain. The weight calculation section calculates an equalization weight based on the channel characteristics of the frequency domain. The equalization filter performs equalization processing of a frequency domain reception signal using the equalization weight.

Channel estimation device, equalization device, and radio system

A correction coefficient calculating sectioncalculates a correction coefficient &#x3b2; so as to obtain a noise power equivalent to detected path and adjacent path transmission channel estimation values. A noise power correcting sectioncalculates a corrected noise power &#x3b2;N. A weight calculating sectionreceives as its input a frequency-domain transmission channel estimation value H(f) being an output of an FFT sectionand the noise power &#x3b2;Ncorrected by the noise power correcting sectionand calculates a weight of an equalization filter by MMSE.

Equalizer and equalization method

The present invention aims to provide a user selection method which can provide a large, multiuser diversity effect with a small amount of calculation in multiuser MIMO systems, the method being a user selection method for multiuser MIMO communication, in which an orthogonal coefficient is calculated using a received SINR from a projection channel vector by using GS orthogonalization, and using the orthogonal coefficient, a correction SINR is calculated, and using this correction SINR, user selection is performed, and for a next user selection, the projection channel vector is updated, and the above processes are applied to all users.

User selection method and user selection device for multiuser MIMO communication

A receiving apparatus, a receiving method, and a radio communications system are disclosed. The receiving apparatus is for receiving CDMA signals transmitted by M antennas and received by N antennas, where M and N are positive integers. The receiving apparatus includes a multipath receiving signal demodulating unit for primary demodulation of the CDMA signals received by the receiving antennas to obtain estimated transmission signals, and for obtaining signals in a multipath environment of each path of the receiving antennas based on the estimated results. Further, the receiving apparatus includes a multipath interference canceling unit for deducting signals of the paths other than a target path from the signals received by the receiving antennas to obtain multipath interference cancelled signals. Further, the receiving apparatus includes a demodulator for secondary demodulation of the multipath interference cancelled signals.

Receiver apparatus, receiving method, and wireless communication system

A reception quality measuring apparatus of the present invention comprises a first sub-carrier averaging unit for averaging and outputting a channel gain after equalization estimated on the basis of the pilot signal over a sub-carrier, a first power calculation unit for calculating the power of a signal output from the first sub-carrier averaging unit and outputting the same as signal power, a pilot replica generator for generating and outputting a pilot signal replica with respect to a zero-timing signal component based on the zero-timing signal component when a signal x(n) in the time domain after equalization corresponding to the equalized signal is n=0, and also based on a previously set pilot code characteristic, a subtractor for subtracting the pilot signal replica output from the pilot replica generator from the equalized signal and outputting the result as an interference signal, a second power calculation unit for calculating and outputting the power of the interference signal output from the subtractor, a second sub-carrier averaging unit for averaging the power output from the second power calculation unit over the sub-carrier and outputting the result as interference power, and a divider for dividing the signal power output from the first power calculation unit by the interference power output from the second sub-carrier averaging unit to calculate a reception quality after equalization.

Reception quality measuring apparatus and reception quality measuring method

A multi-user receiving apparatus is provided for achieving a reduction in the amount of processing for single-carrier FDMA signals and an improvement in reception characteristics. A DFT unit converts single-carrier FDMA received signals of all users to signals in a frequency domain commonly. A demapping unit selects part of sub-carriers for each user from sub-carriers supplied from the DFT unit. A reception filter separates a user signal and suppresses noise. A demodulator demodulates the user signal, and detects a timing thereof.

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Tokyo, Japan

Masayuki Kimata